Air venting and vacuum maintaining valve



June 27, 1939. 'l LASHER M I 2,163,909

AIR VENT'ING AND VACUUM MAINTAINING VALVE Filed Aug. 11, 1934 2 Sheets-Sheet l June 27, 1939.

L. L. LASHER El AL AIR VENTING AND VACUUM MAINTAINiNGNALVE Filed Aug. 11, 1934 2 Sheets-Sheet 2 6 A J a m h l s In 6 9 mm 5 sh v 7. c r. 7 5 WU w 5 y u 2 3 3 3 J) 5 2 2 4, w v z J w .1. J W LEA z a 1 2 J I r p h v. 4 m e fi 3 f S a. M V 7 h Q 9 4. h QVW$VVW a I n. I l".- 7/1 4 4 N\ 113 iv 9% VR f, mu 2 7 Q 0 1 6 JL 2 4. e 1 a W w fi 8 0 0 Patented June 27, 1939 AIR VENTING AND VACUUM MAINTAINING VALVE vLester Lawrence Lasher, Beachmont, Walter Robinson Chesley, Somerville, and Joseph Aloysius Parks, Jr., Milton,

Mass, assignors, by mesne assignments, to Anderson Products, Incorporated, a corporation of Massachusetts Application August 11, 1934, Serial No. 739,424

' 15 Claims. (01.236-63) Our invention relates to automatic air venting valves for steam heating systems.

. In such systems the air which is in the radiators must be. expelled therefrom before the steam generated in the boiler can reach the radiators.

One. of the objects of our invention is to provide an improved valve for allowing the air to escape from the radiator, the valve thereafter closing to prevent escape of the steam.

Another object of our invention is to provide an air valve which will not only close under the influence of steam, but will also close if the valve should become filled with water instead of steam.

A further object of our invention is to prevent ,;the air from re-entering the radiator after gen--' eration of the steam has ceased with the consequent reduction in pressure in the system.

Another object of our invention is to provide a valve soconstructed that the rate of venting of the air'from the radiators on which these 'valves are used maybe controlled or varied. By this arrangement the air under the influence of the oncoming steam may be expelled from all the radiators at approximately the same time. Thus, byproper adjustments our valves permit all the radiators in the system to become heated at the same time and to the same degree, or, if desired, at different times and to different degrees.

An additional object of our invention is to provide a valve for a radiator that will enable the steamto reach that radiator at any desired time in relation. to thetime the steam reaches other radiators.

"Another object of our invention is to provide .an. automatic air venting valve which will close when the pressure within the. radiator is but slightly less than the atmospheric pressure, the closing being effected by a single valve acting without the aid of any auxiliary'vacuum starting valve. I I As evidenced by the patent to Hoffman, 1,708,622, it has heretofore been found necessary in valves of this type to use an auxiliary valve to assist in developing a vacuum sufiiciently great to cause the mainvalve to close, when the steam is cut off and air tends to return to the radiator. By our improved construction the vacuum is maintained by a single main valve.

Another object of our invention is to provide adjustments such that the venting openingcannot be increased beyond a point where the valve closes properly under the influence of steam, or under the influence of reduced internal pressure.

Another novel feature of our invention isthat it is possibleby the adjustment means to entirely close the vent of the radiator when the latter is cold, thus sealing the radiator against any inward or outward movement of the air.

In a few words, the object of our invention is to provide aventing valve for steam radiators which will. properly Vent the airfrom the system, close automatically under the influence of steam or water, maintain its closed position when the internal pressure is reduced, or, if open, close when the internal pressure falls below that of the atmosphere, and at the same time have such adjustability of venting capacity that the heating of the various radiators in the system may be under complete control.

We will now proceed with the description of our invention.

Fig. 1 is a vertical cross section of the valve, the valve being open. 1 g V Fig. 2 is a vertical cross section showing the valve closed under the influence of heat.

Fig. 3 is a vertical cross section showing the valve held closed under the influence of atmospheric pressure, the bellows expanding upwardly as the float is in the process of collapsing.

Fig. 4 is a vertical cross section showing the valve held closed under the influence of atmospheric pressure alone. I

Fig. 5 is a section on 5-5 of Fig. 1 showing the float guide.

Fig. 6 shows a modification wherein the vent block and shell are one piece.

Fig. 7 shows another modification of vent and shell construction.

Fig. 8 shows amodification of our valve.

Fig. 9 shows the use of an auxiliary valve or clapper in conjunction with the main valve.

Fig. 10 shows the valve rendered closed and inoperative by the adjustment means.

Referring now to Fig. 1, which shows the valve in its normal open position, the valve comprises a casing composed of a' base I and a cover portion or shell 2 having a flange 4. This shell is secured to the base by means of a nut 3, the joint between the shell and the base being made steam tight by means of the flange 4 and the washer 5. Having the shell and base separable in this fashion is of advantage, as it enables the valve to be taken apart and cleaned or repaired should it become clogged by impurities from the radiator or otherwise incapacitated. The base I has a hollow, horizontally extending externally threaded nipple 6, which may readily be screwed into a suitably threaded hole of a' steam radiator is a siphon tube 1 which may be secured to the base by any convenient means. As the siphon tube 1 only partially fills the passage in nipple 6, it is possible for steam or air to enter the valve from the radiator, while simultaneously condensate in the valve may be returned to the radiator by means of the siphon tube 1.

A stem 8 threaded at 9 extends upwardly through a centrally located hole, threaded as at H]. The stem can thus be moved vertically with rela tion to the casing as desired within the limits of the engaging threads 9 and i6. To prevent steam from escaping between the stem and the base there is provided a lead washer H and a rubber packing l2 between the threaded portion IU of the base and the gland nut [3, which is screwed into the internal threaded portion M of the base. However, any other suitable means for rendering the base and adjustable stem steam tight may be used.

Mounted on the upper portion of the stem and covering it is a bellows I5, the lower portion of the bellows being secured, preferably by solder, t the collar l6, which collar is in turn secured to the stem by a forced fit and solder or in any other suitable manner capable of rendering the connection air tight. It will be noted that the upper end of the stem extends upwardly within the bellows to such a point that there is but negligible clearance between it and the upper end of the bellows 15. The bellows is so positioned on the stem 8 that when the interior and exterior of the bellows are subjected to' equal pressures, the upper end of the bellows will just graze the upper end of the stem, rendering the bellows incapable of compression. If due to difficulties in manufacture, there should be a space of a few thousandths of an inch between the bellows and the end of stem 8, our invention will not be affected, for such slight compression of the bellows as might result is entirely immaterial in the successful operation of our valve. Thus it will be seen that the bellows cannot be compressed downwardly beyond this point of engagement between the end of the bellows and the upper end of the stem 8. It will further be observed that the bellows can be moved vertically within the casing by the simple expedient of rotating the stem 8. A hole 46 is provided in the lower end of the stem so that any handy implement such as a pin or nail or other small rod may be used to rotate the stem 8.

Extending upwardly from the lower end of the stem, but stopping short of the upper end, is a vertical passage I! which at its top end branches off at 18, thus permitting the atmospheric pressure to reach the interior of the bellows IS. A threaded adjustable stop I9 is also mounted in the base as shown. This stop, it will be observed, has an upper portion 2! of such width that it may engage the collar l6 when the latter is moved downwardly under the influence of the rotatable stem 8. The purpose of stop i9 is to fix definitely the downward limit of movement of bellows l5, beyond which limit the valve would'become inoperative. To prevent subsequent tampering with this adjustment, which is set at the time of assembly, the stop [9 is made sufficiently short so that when in correct position its lower end does not reach the lower surface of the base I. Thus there is a cavity 22 which may be filled with some substance such as solder or plastic material capable of subsequent hardening, rendering further adjustment of the stop impossible. On the other hand, the

lower end of the stop may be left exposed so that it may be adjusted as desired, if for some reason such arrangement might be preferred.

Seated upon the top of the bellows i is a float 23. This float is a cylindrical hermetically 5 sealed vessel containing a volatile liquid as is commonly used in valves of this general type. The bottom of this float, when the valve is in its normal open position, is a concave diaphragm 24, said diaphragm being capable, however, of 10 snapping downwardly to a convex position as shown in Fig. 2, under the influence of internal pressure developed by the volatile liquid therein when heated to the necessary degree. The size and weight of float 23 are also so adjusted that it is capable of floating should water reach and fill the valve.

On the upper end of float 23 is mounted a valve pin 25, said pin being secured in any convenient manner to the float. This pin extends upwardly into a block 26, which block is positioned and secured at the upper end of the shell 2 by means of the threaded engagement 21. Solder or other suitable material is used at the outside juncture of block 26 and the shell 2 in order that this joint may be steam and water tight. Depending from the top and within the float is a stop member whose purpose is to prevent excessive upward flexing of diaphragm 24. 30

Extending axially through the block 26 is the large air passage 28 into which the pin extends, and a smaller passage 29 in the upper portion of the block, said passages 28 and 29 connecting one another and together forming a vent. Between the lower and upper air passages 28 and 29 is the valve seat 30, against which the pin 25 is adapted to seat when urged upwardly by the action of the float 23 or the bellows l5, as shown in Figs. 2 and 4. The valve seat 36 and the valve pin 25 may be of any usual configuration that results in an air tight joint upon engagement one with the other. From the foregoing it will be seen that pin 25 when seated against valve seat 30 under the upward urging of the float or bellows or both, constitutes vent closing means.

Covering the block 26 is a cap 3| having a vent 32 and secured to the block 26 by the threads 33. The cap 3| is not essential to the operation of the valve but is desirable as it keeps out dirt that would otherwise collect on the block 26.

Contained within the shell 2 and loosely surrounding the float 23 is a float guide 34, which is adapted to hold the float in position laterally as the float moves vertically under the influence of the diaphragm 24 or the bellows l5. This float guide may be of any desired design but as used in our invention comprises a spring member that frictionally engages the inside of the shell 2 as shown in Fig. 5.

At this time we desire to call attention to the fact that the venting capacity of our valve may be varied by raising or lowering valve pin 25 by adjusting stem 8. However for any setting of stem 8, the venting capacity remains constant, since, regardless of the pressure within the valve, the bellows cannot be appreciably compressed below its normal position due to the immediate engagement of the end of bellows l5 with the upper end of stem 8.

Having now described the construction of our valve, we shall proceed with a description of its operation.

The valve has of course been secured in the 7 proper vertical position on a steam radiator. The stop I!) is so adjusted that, when the stem 8 is screwed downwardly until the collar l6 engages portion 2| of the stop IS, the pin 25 is a suitable distance below the valve seat 30. The bellows I5 and the diaphragm 24 are in the position shown in Fig. 1. As the steam advances to the radiator from the boiler the air' in the radiator is driven to the atmosphere through the valve, passing through the stem 6 upwardly past the bellows and the float and finally out through the passages 28, 29 and 32. Obviously the rate of venting will depend upon the capacity of the passage between the pin 25 and the valve seat 30, which in turn is controlled by the setting of stop I9 and stem 8.

Upon expelling the air from the radiator and valve the steam is enabled to reach the float 23,

and, when the temperature rises to a predetermined point, the volatile liquid within the float .will expand, forcing the diaphragm 24 downwardly against the top of the bellows l5, as shown in Fig. 2. This in turn causes the pin 25 to move upwardly, seating against the valve seat 30 and thus preventing further escape of the steam. The action of the float so faris the usual action of floats of this type in valves as used heretofore. The bellows I5 is prevented from collapsing under the downward pressure of diaphragm 24 by reason of the upper end of bellows l5 engaging the upper end of stem 8 which stem end is positioned immediately below the normal position of the end of the bellows, as explained heretofore.

It should be pointed out at this point that whatever clearance there may be between the bellows and upper end of the stem is so slight that the collapse of the bellows to that extent has no appreciable effect on the closing ability or venting capacity of the valve. ,7

,As long as the requisite temperature is maintained in the valve the diaphragm 24 will be held in a downward position and the valve will remain closed. When, however, the steam is shut off and the temperature of the volatile liquid within the float 23 is reduced beyond a certain degree, the diaphragm 24 will snap .upwardly, thus allowing the float 23 and pin 25 to drop away from the valve seat 30. This of course would permit air to rush back into the valve and thence into the radiator were it not for the novel means which we are now about to describe.

It will be noted that-upto the present time the bellows l5. has served no purpose other than to provide a support for the float 23. Upon the cutting on of the steam and a subsequent lowering of the temperature within the radiator and valve, condensation takes place, which results in the internal pressure of the valve being less than the outside atmospheric pressure This difference in pressure is well developed before the temper,- ature of the float has receded to a point low enough to permit diaphragm 24 to snap upwardly to normal position as in Fig. 1. Immediately upon the upward snapping of diaphragm 24 the atmospheric pressure entering through the passage l1 exerts an upward force against the under side of the top of the bellows I5 that is greater than the combined internal pressure of the valve and the weight of the float 23 on the upper side of the top of the bellows I5. Due to the sensitive nature of our bellows, this results in an immediate upward elongation of the bellows, causing the pin 25 to be maintained against the valve seat 30 even after the diaphragm 24 has receded to its original position as in Fig. 1. In other words, the

valve, having been closed by the operation ,of the steam on the float, is maintained in closed position, after the shutting ofi of the steam and recession of diaphragm 24, by the upward movement of the bellows, due in turn to the difference in pressure between the inside of the valve and the atmosphere. It should be noted that in the operation just described, when the temperature has receded to the point where the diaphragm 24 snaps upwardly, the difierence in pressure between the interior of the valve and the atmosphere is always sufficient to cause the bellows to follow the receding diaphragm; substantially instantly, thus maintaining the valve in closed position, as shown in Fig. 3.

At this point we wish to call particular attention to the fact that by our invention we are enabled to close our valve when the steam has been turned off without the necessity of using any auxiliary valve.

Thus all the valves in the system are maintained in closed position when the steam is off and a partial vacuum is preserved until such time as the steam goes on again. Upon the resumption of the steam pressure the internal pressure of the valve is increased to a point where it is equal to or exceeds the atmospheric pressure, thus causing the bellows to collapse to a point where the top of the bellows rests on the upper end of stem 8. This lowers the float 23 and reopens the valve. If there is any air in the radiator to be expelled it now passes out, urged by the oncoming steam. When the steam in turn reaches the float the diaphragm 24 snaps downwardly, thus closing the valve, and the opera-tion as described above is repeated.

It should be observed that by varying the opening between the pin 25 and the valve seat 30 by means of the adjustable stem 8 the rate of venting of different radiators can be varied atwill. Thus it is possible to adjust the valves so that a radiator distant from'the boiler may be cleared of air at the same time as a radiator adjacent to the boiler. The advantage of such an arrangement is believed obvious, as it enables all of the radiators to be brought up to full temperature at approximately the same time. It is also apparent that if for any reason it is desired to have certain radiators heat up before others, the valves can be readjusted so that the radiators which are to be heated first will vent more rapidly, or those to be heated last may be adjusted to vent more slowly. This feature of our valve makes it particularly desirable where there are certain rooms in the house that are to be kept warmer than others.

Another mode of operation of our valve which has heretofore, so far as we know, not been possible with other valves, is this: if steam should reach the radiator, but not of suflicient temperature to cause the diaphragm 24 to snap downwardly, it is apparent that the valve would not close, If the valve continued open after the steam was turned off, air would rush back into the radiator through the opening in the block 26, and thus no vacuum would be set up in the system. To overcome this difficulty we have constructed our bellows in such a way that it is very sensitive to small differences in pressures. Thus when the steam is turned off and condensation in the radiator or boiler takes place, a slight reduction in pressure inside the valve develops, even though the air can at the time enter through the open valve in theblock 26. However, due to the particularly sensitive construction of our bellows, this slight reduction in pressure within the valve is sufficient to enable the atmospheric pressure, entering through passage 61, to force the bellows upwardly a distance sufficient to close the valve. Since the diiierence in pressure needed to effect this closing is very slight, the closing takes place almost immediately after the initial collapse of the steam, thus reducing to a minimum the amount of air that has entered through the valve before the closing is effected.

We believe we are the first to produce a valve of this type having adjustable venting capacity, but of invariable venting capacity at any given adjustment, and at the same time capable of closing when the internal pressure is but slightly reduced below atmospheric pressure without resort to auxiliary vacuum developing means. The pressure difference necessary to close our valve or to keep it closed if it had previously been closed by the operation of the float, is less than the difference in pressure that is promptly developed in the ordinary steam heating system upon the turning off of the steam. This is the desideratum that has been sought for many years, but as far as we know has never been accomplished prior to our invention.

In certain very extreme cases where the vacuum developed in the system may be so slight as to cause a pressure difference between the atmosphere and the internal valve pressure insufficient to effect elongationof the bellows to close the vent, we have found it desirable to use an auxiliary valve or clapper 35 as shown in Fig. 9. This enables what little vacuum is developed to be retained without the operation of the main valve. Of course if the vacuum should subsequently develop to the minimum point necessary to operate the bellows and main valve, then the vacum would be maintained by both the auxiliary and main valves.

Ordinarily, however, no auxiliary valve or clapper is necessary, as the vacuum created under usual operating conditions is always sufiicient to operate the bellows to close the main valve.

A further mode of operation of our valve is this: if it is desired to render a radiator entirely inoperative it is possible by means of the vertically adjustable stem 8 to screw the stem upwardly until. the pin 25 is forced against the valve seat 38, as shown in Fig. 10 thus closing the valve until reopened by screwing stem 8 downward.

Fig. 6 shows a modified form of vent and shell construction wherein the vent block 26 is made integral with the shell of the casing 2.

7 shows another modification of the vent and shell construction. Here the cap and shell are made of one piece and the vent block 26 is inserted in the cap cavity, being secured by a press fit, as shown, or by any other suitable means.

Fig. 8 shows a modification of our valve wherein the nipple 6, instead of extending sidewise from the casing, is projected downwardly thus enabling the valve to be attached to the top of a radiator or steam heater. No siphon tube is necessary with this construction as the condensate in the valve will drain back to the radiator through nipple 6 without interfering with the incoming air or steam.

It will be noted that this nipple extends in a direction substantially parallel to the longitudinal axis of our valve, but it is located at a sufficient distance to one side to'avoid any interference with our adjustment stem 8 or the stop 19. I-Ieretoiore adjustable valves having straight shanks have been made with the shank co-axial with the axis of the valve, thus rendering it incapable of adjustment without removing the valve from the radiator. By our arrangement the adjustments of the valve can be made without removing it from the radiator. This is particularly advantageous when used with the socalled concealed radiation heating systems, which comprise radiators concealed by a grillwork. In such systems the air valve is usually positioned on top of the end section of the radiator, rather than on the side, as is customary in conventional type systems. Thus it is obvious that it is of considerable advantage to have our straight shank valve so constructed as to be adjustable without removal from its position on the radiator.

Thus it can be seen that by the combination of elements that we have invented our valve gives complete control of the distribution of steam or vapor in a one-pipe steam heating system. A valve giving such control we believe to be distinctly new, and we desire to claim our con struction as broadly as possible.

As at present constructed our valve is made preferably of metal, although phenol condensation products, such as Bakelite, may be used for the base and outer shell and other parts that lend themselves to manufacture by such materials.

We claim:

1. In a radiator air venting valve, the combination of a casing having a vent, an adjustable stem mounted in the base of said casing, a bellows mounted on said stem, an air passage through said stem to allow atmospheric pressure to reach the interior of said bellows, and buoyant means between said bellows and vent operable to close said vent when said casing is filled with water to a predetermined extent.

2. In an air venting valve for steam radiators and the like, the combination of a casing having a vent, a stem mounted in the base of said casing, and adjustable toward and away from said vent, said stem supporting and extending upwardly into a bellows, the upper end of said stem being at a point immediately below the normal position of the upper end of said bellows to support said bellows against collapse, an opening through said stem to admit atmospheric pressure to the interior of the bellows, a stop mounted in the casing to limit the downward adjustment of the stem and bellows, an expansible thermostatic float resting on said bellows, a valve pin mounted on said float capable of closing said vent when said float is expanded under the influence of heat.

3. In an air venting valve for steam radiators and the like, the combination of a casing having a vent, a stem mounted in the base of said casing, said stem adjustable toward and away from said vent, said stem supporting and extending upwardly into a bellows, the upper end of said stem being at a point immediately below the normal position of the upper end of said bellows to support said bellows against collapse, an opening through said stem to admit atmospheric pressure to the interior of the bellows, a stop mounted in the casing to limit the downward adjustment of the stem and bellows, an expansible thermostatic float resting on said bellows, a valve pin mounted on said float capable of closing said vent when said float is raised by water within the casing.

4. An air venting valve for a radiator comprising a casing with a vent fixed with relation to said casing, said vent normally open for passage of air in either direction when the internal pressure of the valve equals the atmospheric pressure, and

means for closing said vent against inrushing air when the internal valve pressure is less than atmospheric pressure, said means comprising a bellows adjustably mounted on a hollow stem, said bellows interiorly exposed to the atmospheric pressure and exteriorly exposed to the internal casing pressure, and buoyant means between said bellows and vent operable to close said vent when said casing is filled with water to a predetermined extent.

5. In a radiator air venting valve, the combination of a casing having a vent, an adjustable stem mounted in the base of said casing, a bellows mounted on said stem, means permitting atmospheric pressure to reach one side only of the bellows, and buoyant means between said bellows and vent operable to close said vent when said casing is filled with water to a predetermined extent.

6. In an air venting valve for steam radiators and the like, the combination of a casing having a vent, a stem mounted in the base of said casing, said stem adjustable toward and away from said vent, said stem supporting and extending upwardly into a bellows, the upper end of said stem being at a point immediately below the normal position of the upper end of said bellows to supportsaid bellows against collapse, an opening through said stem to admit atmospheric pressure to the interior of the bellows, a stop mounted in the casing to limit the downward adjustment of the stem and bellows, an expansible thermostatic float resting on said bellows, a valve pin mounted on. said float capable of closing said vent when said float is raised by the elongation of said bellows under the influence of atmospheric pressure greater than the internal valve pressure.

7. A radiator air venting valve comprising the combination of a base and a shell attached thereto, said shell having a vent, and means for closing said vent comprising a valve pin mounted on a float, said float supported by a bellows adjustably mounted on said base, said bellows capable of axial expansion under the influence of atmospheric pressure greater than the internal valve pressure, but substantially incapable of collapse when the atmospheric pressure is less than the internal valve pressure.

8. In a radiator air venting valve, a casing comprising a base and shell, a vent in said shell, means mounted on the base for closing said vent when said valve is filled with water to a predetermined extent comprising a float carrying a valve pin, a bellows supporting said float and adjusta'bly mounted on the base, said bellows operated by pressure differences, but substantially incapable of compression below its normal length.

9. In a radiator air valve, the combination of a casing comprising a base and shell, said shell having a vent therein, and vent closing means, said means comprising a bellows adjustably mounted on said base, for varying the venting capacity of the valve, said bellows exposed to the atmosphere on one side and internal valve pressure on the other, a thermostatic float carrying a valve pin mounted on said bellows, said pin capable of closing said vent against the movement of air in either direction when moved by the operation of said bellows or float, and an auxiliary valve capable of closing the vent against the movement of air in one direction only.

10. In a radiator air venting valve, the combination of a casing having a vent, adjustable means mounted in said casing supporting a bellows, means permitting atmospheric pressure to reach one side only of the bellows, means supported by said bellows capable of closing said vent, and a nipple, whose axis is generally parallel to the axis of the vent closing means, extending from said base, said nipple being positioned adjacent said adjustable means, to permit access to said adjustable means.

11. In a radiator air valve, the combination of a casing comprising a base and shell, said shell having a vent therein, and vent closing means, said means comprising a bellows adjustably mounted on said base for varying the venting rate of the valve, said bellows exposed to the atmosphere on one side and internal valve pressure on the other, a thermostatic float carrying a valve pin mounted on said bellows, said pin capable of closing said vent against the movement of air in either direction when moved by the operation of said bellows or float, and a nipple whose axis is generally parallel to the axis of the vent closing means extending from said base, said nipple being positioned adjacent said adjustable means, to permit access to said adjustable means.

12. In a radiator air-venting valve, the combination of a casing having a vent therein and vent-closing means comprising a main valve adjustable to vary the rate of venting and operative under the influence of heat, pressure, or water in the valve, to close said vent against the movement of fluid in either direction, said adjustable mechanism having associated therewith an adjustable stop to limit the amount said valve may be opened.

13. In a radiator air venting valve, a casing comprising a base and shell, said shell having a vent, adjustable vent closing means comprising a float and an atmospherically operated bellows axially arranged on said base, a nipple whose axis is generally parallel to the axis of the vent closing means extending from said base, said nipple being positioned laterally of said adjustable means to permit access to said adjustable means.

14. In a radiator air venting valve, the combination of a casing having a vent, a float for closing said valve when said casing is filled with water to a predetermined extent and a bellows positioned within said casing and each capable of closing said vent independently of the other, a tubular member associated with said bellows to permit the atmosphere to reach one side only of said bellows, and means whereby said float, bellows and tubular member may be adjusted with respect to said vent to vary the venting rate.

15. In a radiator air venting valve, the combination of a casing having a vent, an adjustable stem mounted in the base of said casing, a unit that elongates when the internal valve pressure is less than atmospheric, said unit mounted on said stem, an air passage through said stem to allow atmospheric pressure to reach the interior of said unit, and buoyant means also supported by said stem capable of causing the closure of said vent when said casing is filled with water to a predetermined extent.

LESTER LAWRENCE LASHER. WALTER ROBINSON CHESLEY. JOSEPH ALOYSIUS PARKS. JR. 

